The incorporation of electronic devices with pneumatic tire structures yields many practical advantages. Tire electronics may include sensors and other components for obtaining information regarding various physical parameters of a tire, such as temperature, pressure, number of tire revolutions, vehicle speed, number of rotations at speed, temperature at speed and other physical and operational parameters as well as manufacturing information such as name of manufacturer, manufacturing location, date of manufacture, etc. Such performance information may become useful in tire monitoring and warning systems, and may even potentially be employed with feedback systems to regulate proper tire pressure levels. For example, differences in tire rotational speed on the same vehicle may be indicative of under or over inflation as the diameter of a tire will change slightly with inflation pressure.
U.S. Pat. No. 5,749,984 (Frey et al.) discloses a tire monitoring system and method that is capable of determining such information as tire deflection, tire speed, and number of tire revolutions. Another example of a tire electronics system can be found in U.S. Pat. No. 4,510,484 (Snyder), which concerns an abnormal tire condition warning system. U.S. Pat. No. 4,862,486 (Wing et al.) also relates to tire electronics, and more particularly discloses an exemplary revolution counter for use in conjunction with automotive and truck tires.
Yet another potential capability offered by electronics systems integrated with tire structures corresponds to asset tracking and performance characterization for commercial vehicular applications. Commercial truck fleets, aviation crafts and earthmover/mining vehicles are all viable industries that could utilize the benefits of tire electronic systems and related information transmission. Tire sensors can determine the distance each tire in a vehicle has traveled and thus aid in maintenance planning for such commercial systems. Vehicle location and performance can be optimized for more expensive applications such as those concerning earth-mining equipment. Entire fleets of vehicles could be tracked using RF tag transmission, exemplary aspects of which are disclosed in U.S. Pat. No. 5,457,447 (Ghaem et al.).
Such integrated tire electronics systems have conventionally been powered by a variety of techniques and different power generation systems. Examples include mechanical features for generating energy from tire movement, non-rechargeable batteries, and scavenging RF beam power with an interrogation antenna in close proximity to a tire.
In accordance with the present subject matter, it is appreciated that certain advantages of piezoelectric materials have long been recognized. However, such technology is constantly improving, thus potentially affording applications that utilize piezoelectric materials with improved operating capabilities. Examples of relatively new advances in piezoelectric technology are provided in U.S. Pat. No. 5,869,189 (Hagood, IV et al.) and U.S. Pat. No. 6,048,622 (Hagood, IV et al.), directed to composites for structural control. The presently disclosed technology concerns further advances in piezoelectric technology such that a piezoelectric sensor may be combined with other or existing tire condition related electronic sensors and together can be integrated with a tire or wheel assembly.
The disclosures of all of the foregoing United States patents are hereby fully incorporated into this application for all purposes by reference thereto. While various implementations of piezoelectric sensor devices have been developed for use with tire electronic systems, and while various combinations of information have been wirelessly relayed from a tire or wheel assembly using conventional technologies, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.